Luminous areas are generally used for backlighting objects, for example, for backlighting billboards. In the case of luminous areas of this type, one or more light sources is or are arranged at a relatively large distance behind the object to be backlit. In order that the light emitted in substantially punctiform fashion by a light source, for example, a light-emitting diode, is distributed over a larger area, a diffusing film is arranged between the object to be backlit and the light source. In order that the light emitted by the light source can be diffused over a sufficiently large area by the diffusing film, the light source is generally arranged at a distance of more than 50 mm before the diffusing film. The actual object to be backlit is arranged once again at a distance from the diffusing film.
Luminous areas having a construction of this type therefore have a high structural height. In order to reduce the structural height, it is possible, for example, to use very bright light sources. Use is made, for example, of light sources using CCFL (cold cathode fluorescent lighting) technology, and also fluorescent lamps or LED backlights. When using such light sources, although the structural height can be reduced somewhat, the object is often backlit in a manner that is no longer uniform. In order to prevent darkened regions of the backlit object from arising, it is necessary to use a multiplicity of light sources arranged at a distance behind the object to be backlit.